小型γ相机压缩效应的实验研究

在一套平板式晶体单管γ相机上,研究了闪烁晶体的选择和处理对γ相机性能的影响.结果表明:(1)采用侧面吸收的光学边界条件可以上大减小压缩效应;(2)晶体的发光效率对相机的固有空间分辨率影响很大,对于准直孔直径为2mm的241源,采用CsI(T1)晶体时相机的固有空间分辨率为～1cm,采用NaI(T1)晶体时为～0.4cm.     

Experimental research into the two-proton emissions from ~(17,18) Ne,~(28) P and ~(28,29)S

Two-proton emissions from the excited states of 17,18Ne, 28P and 28,29S were investigated experimentally by the radioactive beams bombarding on the 197Au target via the Coulomb excitation. The complete-kinematics measurements were actualized by the stacks of silicon-strip detectors and CsI+PIN array detectors. The invariant mass of final systems as well as the relative momentum, opening angle, and relative energy of the two emitted protons was reconstructed under the framework of relativ istic kinematics. V...     

Study of proton resonances in ~(18)Ne via resonant elastic scattering of ~(17)F+p and its astrophysical implication

The proton resonant properties in 18Ne, which determine the reaction rate of the key stellar 14O(α,p)17F reaction, have been studied by using a technique of proton resonant elastic scattering of 17F+p. A 4.22 MeV/nucleon 17F radioactive ion (RI) beam was produced via a projectile-fragmentation reaction, and separated by a Radioactive Ion Beam Line in Lanzhou (RIBLL). By bombarding a thick (CH2)n target, the energy spectra of the recoiled protons were measured by two ΔE-E silicon telescopes at the center-of-...     

Experimental Study on Image Shrinkage in a Planar Crystal γ Camera

The effect of the crystal's type and treatment on the performance of gamma camera consisting of planar crystal and position sensitive photomulitiplier tube (PSPMT) is studied via experiment. The results demonstrate that: (1) treatment of the edge surface of the crystal is very sensitive to the shrinkage of image, and the side-absorptionsurface is the best choice; (2) the intrinsic spatial resolution of the CsI (T1) crystal camera is worse due to its low light yield: in the center part it is - 1cm (FWHM) for 2mm aperture collirnated 241Am source; while using NaI(T1) crystal, it is -4mm.     

Study of proton resonances in 18Ne via resonant elastic scattering of 17F+p and its astrophysical implication

The proton resonant properties in ¹⁸Ne, which determine the reaction rate of the key stellar ¹⁴O(α,p)¹⁷F reaction, have been studied by using a technique of proton resonant elastic scattering of ¹⁷F+p. A 4.22 MeV/nucleon ¹⁷F radioactive ion (RI) beam was produced via a projectile-fragmentation reaction, and separated by a Radioactive Ion Beam Line in Lanzhou (RIBLL). By bombarding a thick (C_H2) _n target, the energy spectra of the recoiled protons were measured by two ΔE-E silicon telescopes at the center-of-mass scattering angles of θ _c.m.≈175°±5°, θ _c.m.≈152°±8°, respectively. Several proton resonances in ¹⁸Ne were observed clearly. A further R-matrix analysis of the experimental data is under way to determine the resonant parameters. The present work reports the preliminary results briefly.     

Experimental research into the two-proton emissions from 17,18Ne, 28P and 28,29S

Two-proton emissions from the excited states of ^17,18Ne, ²⁸P and ^28,29S were investigated experimentally by the radioactive beams bombarding on the ¹⁹⁷Au target via the Coulomb excitation. The complete-kinematics measurements were actualized by the stacks of silicon-strip detectors and CsI+PIN array detectors. The invariant mass of final systems as well as the relative momentum, opening angle, and relative energy of the two emitted protons was reconstructed under the framework of relativistic kinematics. Visible proton-proton correlations were observed in these systems. The mechanisms of two-proton emission were analyzed in a simple schematic model, in which the extreme decay modes like ²He cluster emission, three-body phase-space decay, and two-body sequential decay were taken into account. With the help of Monte-Carlo simulations, the two protons emitted from the 6.15 MeV excited state of ¹⁸Ne and the excited states in the energy region of 9.6–10.4 MeV of ²⁹S, respectively, exhibited prominent features of ²He cluster decay while for the other cases, no obvious diproton emissions were observed.